I think there is some info in here. hopefully my file post works........ah damn the file is too big. ok i posted some pictures of the manual and how it says to lube.
SWAT magazine had an article written by Pat Rogers on lubrication of the AR series rifles. I have the mag but I think that the website has back issues available to purchase. If I think about it tonight, I'll look up which issue it was.
While there are a bunch of loonies, mall ninjas, and people who will steer you wrong on ar15.com, you can find quite a bit of good reference material and walkthroughs for straightforward things like cleaning, lubing, and preventative maintenance there.